The advanced charger HV is based on a hardware pratically identical to the non HV version: for this all the material (from the schematics to the PCB) can be dowloaded from the Advanced Charger version. The only differences between the two models are below listed with a detailed description.



The minimal change for a complete high voltage charger are the following:

1. Power supply with a 24V source (Current equal to maximum charge current).
2. Change the R6 with 12 KOhm, 1% value.
3. Heat sink the 7805 regulator.
4. Change the fan cooler with a 24V model.
5. Reprogram the PIC with the newch_HV.HEX file (see "files" section).
6. Start the charge/discharge of your 14-cells pack!!!.

The resistor R6 and R5 are the input partitor for the battery voltage. This resistor in the Advanced Charger has a 33KOhm value for an input range of 12V, in the HV version this resistor has a value of 12KOhm for 24V input range. If the user uses others values or want to take into account the resistor tolerances can use the "CUSTOMIZATION" section in the assembler file and enter the exact value for these resistors. In this case the file must be recompiled.


If the power supply voltage is above 15V it is better to have an heat sink on the 7805 regulator in order to prevent excessive temperature on this component.


The power supply must be changed following the number of the cells to be charged. A simple rule for this is to multiply the number of cells for 1.6V and add 1.5V: with this rule the power supply of 24V is sufficient for 14 cells. This depends obviously from the cell voltage (high quality cells have a higher voltage): for this is necessary to try the charge process and check if the charge current is always at the set value.


The fan cooler must be changed because the PC fan has 12V power supply and does not work at 24V. The user can buy directly a 24V fan or lower the voltage on the fan with a resistor or regulator.


The improvements introduced in the HV firmware are the following:

1. In this version the R5 and R6 resistor values are moved in an assembler code separated section named "USER CUSTOMIZATION" for easier editing.The assembler file must be recompiled and the PIC reprogrammed in order to make effective the change of this parameter.
2. Another improvement possible is the setting of the maximum current when in "power supply" mode. This parameter is present in the "USER CUSTOMIZATION" section and is an integer representing the max amperes delivered to the load. The assembler file must be recompiled and the PIC reprogrammed in order to make effective the change of this parameter.
3. The buzzer tone frequency is another customizable constant. This parameter is present in the "USER CUSTOMIZATION" section and is useful when the charger must drive a buzzer with a "resonant" frequency different from 2KHz. The assembler file must be recompiled and the PIC reprogrammed in order to make effective the change of this parameter.
4. The buzzer tone at the end of the charge or discharge process has a fixed duration of about 20 seconds.
5. The run-time firmware has a unique change in the setting of the cell number: this number can be from 1 to 19.